Adjustable reference marker indicating system for echo ranging devices



July 15, 1952 M. s. McvAY ET AL 2,603,778

DJUSTABLE REFERENCE MARKER INDICATING SYSTEM FOR ECHO RANGING DEVICESFiled Dec. 26, 1947 gwuemom MILLARD S. MC VAY JOHN H. GREIG tions, whichappear as small arcs,

Patented Juy l5, 1952l s PATENT OFFICE ADJUSTABLE REFERENCE MARKER INDI-CATING SYSTEM FOR ECHO RANGING DEVICES Millard Si. McVay, .WashingtornD. C., and John H. Greig,New York, N. Y.

Continuation of application Serial No. 441,732, May 4, 1942. Thisapplication'December 26, 1947, Serial No. 794,073

8 Claims. (Cl. 343-.'11)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 7-57) This .invention relates to indicating systems and moreparticularlyA to means for facilitating the interpretation ofindications produced by radio echo ranging devices or Similarapparatuses.

Certain radio echo ranging apparatuses include means for detecting thepresence of all remote objects included within a field extending360.about the apparatus, means for determining the range and directionof the detected objects with respect to the apparatus, and suitableindicating means, such as a cathode ray oscilloscope, for providing avisual plan representation of theV area extending 360 about theapparatus upon which indications of the detected remote objects areproduced in such a manner to simultaneously show range and directionthereof.

More particularly, the foregoing types of radio echo ranging apparatusinclude a directional beam antenna supplied with a source of energy forproducing a highly directional beam of energy.A The antenna iscontinually rotated in. order to scan an area 360 about the apparatuswith such directional energy whereby the energy is reflected from allobjects included within the scanned area. Such apparatuses furtherinclude means for producing a radial sweep on the cathode rayoscillograph which rotates in synchronism with rotation of thedirectional beam antenna so that the radial sweep at all times radiallypropagates in a direction which corresponds to the direction of thesource of energy from the antenna. Means are also provided for receivingreections of the energy from remote objects and for modulating theintensity of the sweepl line on the' oscillograph whenever reectedenergy is received. By proper synchronization of the rate of emission ofthe directive energy with the rate of propagation of the radial sweepthe positions of reflected energy indications on the sweep lines are adirect measurement of range of remote objects, lwhile the angularposition of the sweep line at the instant indications appear thereonrepresents the direction of remote objects. In operation of an apparatusof the above type, the intensity vof the radial sweep is modulated insuch a manner that only reflected energy indicathe length ofwhich-varies with the range, are only visible on the oscilloscopescreen. With an indication of the foregoing type it becomes extremelydifilcult to accurately determinev Athe range and direction of remoteobjects since reference indications of range and direction are notprovided. It -is therefore anobject of the present invention to providenovel means for facilitating the interpretation of indications producedby certain kradio echo ranging devices or similar apparatuses.

Another object isto provide a radio echo ranging apparatus having novelindicating means whereby range and direction of remote objects arequickly obtained with a high degree of accuracy. Y

Still another object of the invention is to provide novel means forfacilitating the determination Yof range and direction of a pre-selectedremote object with a high degree of accuracy.

Still another object is to provide a discontinuous circular mark on theoscilloscope screen with means for Varying the radius of rthe mark as afunction of range and the angular position of the discontinuous'po'rtionof the mark as a function of direction.

Stili another object is to provide an indication of the foregoingcharacter with novel means for indicating the radius of the circularmark and. the angular position of the discontinuous portion thereofrespectively as functions of range and direction.

Other objects and features of the invention will appear more fully fromthe following detailed description when considered in connection withthe accompanying drawing which discloses one embodiment of theinvention. It is to be expressly understood, however, that the drawingisY designed vfor purposes 'of illustration only and not as a denitionof the limits of the invention. reference forthe latter purpose beinghad to the appended claims.

In the drawing, wherein similar reference characters denote similarelements throughoutV the several views; Y

Fig. 1 is a diagrammatic showing of a radio echo ranging apparatusembodying the principles of the present invention, and

Fig. 2 is an illustration of the calibrating mark produced on viewingscreen of the oscilloscope disclosed in Fig. l.

With reference more particularly to Fig. 1, a radio echo rangingapparatus is disclosed therein including a rotatable directional beamantenna I0 and an individual connection between the'an-Y tenna andreceiver I3 so that a single antenna may be employed for transmission aswell as reception. A duplexingcircuit constructed in accordance with theprinciples disclosed in the patent to Wolff and Hershberger, 2,401,717,led January 11, 1938, and issued June 4, 1946. Antenna III may take theform of any directional beam antenna capable of producing a highlydirective beam of energy, while transmitter I2 and receiver I3 areconstructed in such a manner to properly transmit and receive radiopulses, the types of transmitters and receivers employed in conventionaltelevision systemsl are suitable for these purposes. controlled byelectronic keyer I5 in such a manner that equally spaced radio pulsesare emitted therefrom at a predetermined rate. Oscillograph II isprovided with electro-magnetic deflection coils I6 mounted onanti-friction bearings for rotation about the oscilloscope. Deflectioncoils I6 are wound in such a manner to produce varying magnetic lines offorce Within the oscilloscope, when saw-tooth varying current is appliedthereto, with a source of direct current, for deflecting the beam ofelectrons generated withinthe oscilloscope in a radial direction fromthe center of e the oscilloscope, upon application of each sawtooth Waveform. Such deflection ofthe electron beam produces a radial sweep ortrace a on viewingscreen I'Iof oscilloscope II. By proper. ad'-Ajustment of bias supply I 3 theintensity of the electron beam isnormally modulated so thatthe radial. sweep a is not visible. Saw-toothwave generator I5 is provided for applying saw-tooth wave forms, as wellas a source of direct current, to deflection coils I6y through suitableslip rings. Synchronizer 2G is employed, With connections to electronickeyer I5 and saw-tooth waveV generator I9, in order to properlysynchronize the pulse emitted from transmitter I 2 With the applicationof saw-tooth Wave forms to deflection coils I6. Antenna I iscontinuously rotated byrmeansof motor 22, the latter beingrotatablyconnected to the antenna through gear reduction means 23.

and shaft 24. In order to rotate the radialsweep a in'synchronism withrotation of antenna I3., deflection coils I6 are rotated by motor 22,through pinion 25, and annular gear.26 mounted on the outer periphery ofthe deflection coils. The arrangement is such that the energy emissionfrom antenna Il] and the radial propagation` of the electrical beam areat all times in the same direction. Whenever radio pulses emitted fromantenna I9 impinge upon remote objects, echo.

pulses are reflected from the objects, passed to receiver I3 whereinsuch echo pulses are suitably amplied and subsequently applied tointensity control grid ZI to modulate the intensity of the electron'beamthus producing visual indication ony screen I'I.

In operation of theA radio echo ranging apparatus disclosed in Fig. 1,motor '22Y continually rotates antenna II) and deflection coils I6 insynchronism. The highly directive beam of energy from antenna I8, whichcomprises radio pulses propagating at a constant rate, is thuscontinually `scanned overy an area extending 360V about the antenna.-The application of saw-tooth varying current from generator Ill-todeflection.

coils I6 produces a radial sweep line a on viewing screen I'I, ofoscilloscope II, which rotates in 'synchronism with rotation of thedirective beam of 'energy emitted from the antenna. Synchronizer 26'controls operation of electronic keyer I and saw-tooth wave generator I9in such a manner that a radio pulse is emitted from transmitter I2simultaneously with application of every saw-tooth wave form todeflection coils I E. Whenever radio pulses emitted from-the antennaimpinge upon remote objects, echo pulses are reflected from the objects,received at antenna Ii) and passed through a channel of duplexing4circuitv II to receiver I3. The echo pulses are properly amplied by'receiver I3 and applied to intensity control grid 2I of the oscilloscopeto modulate the intensity of the electron beam thereof thus producing anindication on oscilloscope screen I'I. Due to operation of synchronizer20, such pulse indications appear at various distances from the centerof the oscilloscope screen I l in direct proportion to the range ofremote objects, from which echo pulses are reiiected, with respect toantenna II). Since antenna I and sweep line a rotate in synchronism.echo pulse indications from remote objects appear on oscilloscope I'I atvarious angular positions that correspond to the angularv position ofremote objects with respect to antenna IIL The foregoing type of radioecho ranging ap- A' paratus thus provides a visual plan'indication of,the area continually scanned by the, highly directive source of energyvemitted Vfrom anteni'iar IB, which, in the presentinstance, comprisesthe` viewing. screen I'I ef the oscilloscope.. I Indica--,

tions of remote objects are produced'onviewing screen I'I in such amanner that range and dif rection of all remote. objects included Withinthe -eldscanned by the rdirective beam ofenergyf from thevantenna aresimultaneously shown.r Invv Fig. l, indications of remoteobjectspdesignated by Z7, are shown on viewing screen I1, atv various'.radial distances from the center of the oscille-W graph screen and atdifferent angular positions thereon. Indications b represent positionsof remote objects with respect toantenn'a I Il; the angular` positionsofthe indications, with respect to the center of viewing screen I'I,representy directions of such remote objects with respect to J antennaII), While theradial distance of the,in-,

dications from the centerof screen I'IcorrespondI to the range ofremoterobjects withrespectfto the antenna. As mentioned heretofore,'bias supply I9 is adjusted in such a manner asfto.

modulate the intensity` of thevelectron beamQof.

oscilloscope II so that sweep line a is not visible;

therefore, remote object indications b 'areonlyv visible on screen I 'I,

As mentioned heretofore, meansareprovided, by the present invention forfacilitatingltheinjoterpretation of remote object indications b'wherer.

by range and direction of remote objects are ing Vscreen of theoscillograph, symmetrical with:

respect to thercenterof the screen, with-means.; for varying andindicating the radius ofthe c1151; Culanmark as a functionpof range,aslwell-,asy means for. angularlyvarying and indicating1 the` positionof the discontinuous portion of .tliemazfli` as a function of direction,Withftheforegoin'gl arrangement, by proper `^variations Aof *thevradius'. of the` circular mark andthe-angular positionv of the,discontinuous portion thereoffthccircular mark maybe. moved to aposition whereinA av reniote object b is `symmetrically ,positionedwithin the discontinuous portion. Range and direction of theremoteobject represented by the indication b is thus directly obtained fromsuitableindicating means associated with the apparatus. When the rangeand direction of the remote object varies, the radius and angularposition of the discontinuous circular mark is Varied to maintain theremote object indication symmetrically positioned within thediscontinuous portion whereby continuous indications of range anddirection are provided.

In order to produce a Calibrating mark of the foregoing. character novelmeans are provided by the present invention for generatingj'a positiveimpulse which is applied to intensity control grid 2| of oscilloscopeIl. The generation of such impulses are properly synchronized with theradial propagation of the electron beam, as well: aswith the rate ofpulse generation at transmitter I2, in order to provide indications onscreen I1 of a certain range calibration which corresponds to the rangecalibration of sweep line a. The positive impulses are applied tointensity control grid 2l in synchronism with application of saw-toothcurrent wave forms to deflection coils I6 for a substantially largeperiod of time during each complete revolution of the radiallypropagating electron beam to thus produce a discontinuous circle onscreen I1 upon each complete revolution of antenna I6.

As shown in Fig. 1, the device for generating a positive impulse duringthe period of each radial propagation of the electron beam includesVacuum tube 30 which is triggered upon application'of a positive impulseto the grid thereof from electronic keyer I simultaneously withgeneration of a pulse at transmitter I2. Tube 30 ,thus generates anegative impulse which is applied to the control grid of vacuum tube 3I.Tube 3l is interconnected with vacuum tube 32 to form a multi-vibratorcircuit which comprises a two-stage capacitance coupled amplifier withregenerative feedback. When a negative impulse is applied to the controlgrid of tube 3l, the tube is blocked, thus applying a positive bias tothe control grid of'tube 32, rendering the latter tube conducting andproducing a potential drop at the plate thereof; The plate of tube 32remains at a low potentialfor a period of time determined by the valuesof grid resistances 33, 33 and capacitances 34, 34 associated with thecontrol grids of tubes 3I and 32. The negative impulse output of tube 32is applied to the control grid of vacuum tube 35. Tube 35 is normallymaintained in a conducting state by proper selectionv of plate resistors36 and grid resistor 31 and is blocked vupon application of a negativeimpulse to the control grid thereof. Capacitance 33 is connected acrossthe plate and cathode of tube 35 and charges exponentially throughresistor 36 when tube 35 is in a non-conducting state. The exponentiallyincreasing potential of capacitance 38 isf applied through a windingoftransformer 40v to the control grid of tube 4I.l Tube 4I isnormallymaintained in a non-conducting state and the'cut-oipotentialthereof is varied by means .of .potentiometer 4.2 in order to determinethe time that tube 4l is rendered conducting following the instantcapacitance 38 commences to .charge exponentially. For a purpose thatwill. appear more fully hereinafter, potentiometer 42. isj:-adjustableupon manual rotation Vof dial 43. A,"I'ransformer 46 has connectionswith the in. When theexponentially increasing chargeY of capacitance 38reaches a suicient value to render tube 4I conducting, a negativeimpulse` is generated at the output thereof, and oscillations commencein the oscillatory kcircuit between the plate and control grid of thetube. Resistances 44 and 45, however, damp suchoscillations to onlyallow generation of a single positive impulse following generation ofthe negative impulse. The output of tube 4I is connected throughcondenser 46 to the control grid of amplier tube 41 which is normallybiased in a conducting state. When the negative impulse output of tube4I is applied to the control grid of tube 41 the latter tube is blockedfor an interval of time determined by the duration of the negativeimpulse, during which time a positive impulse is generated at the outputof tube 4.1. The amplitude of the positive impulse generated at theoutput of tube 41 is controlled by adjustment of potentiometer device48. The output of tube 4I is also applied through condenser 49 to thecontrol grid of vacuum tube 5i) to re-set the multi-vibrator. When thepositive impulse from tube 4I is applied to the grid of tube 50, thetube draws current thus producing a drop in potential at the grid oftube 32, blocking the latter tube. Tube 3| is driven conducting, and themulti-vibrator is thus re-set to a condition responsivev to applicationof the next negative impulse from tube 30.

The positive pulse output of tube 41 is applied to intensity controlgrid 2I to modulate the intensity of the electron beam at a certaininstant during every radial propagation of the electron beam. In orderto prevent application of the positive impulses during a certain periodof each complete revolution of the radial propagating electron beam tothus produce a' discontinuous circular mark on screen I1, suitableswitching means are provided for controlling application of the positiveimpulses to grid 2I. Such means comprises a cylindrical member 60, ofinsulating material, rotatably mounted on shaft 24 for synchronousrotation with antenna IU. A discontinuous circular metallic conductor 6Iis imbedded in the outer periphery of member 60 andis electricallyconnected through suitable slip rings, not shown, to the output 0f..tube41 .by way of electricalV conductor 62. Stationary. contacts 63 aremounted on angular ring 64 and is electrically connected to intensitycontrol grid 2I. With the foregoing arrangement, the positive impulseoutput of tube 41 is applied to intensity control grid 2l only duringthe time when electrical contact is maintained between conductor 6I andstationary contact 63. Since conductor 6I contacts stationary contact 63for a greater period during each revolution of shaft 24 the output oftube 41 is applied to intensity control grid 2l during a greater portionof each complete revolution of shaft 24. A discontinuous circularcalibration mark is thus produced on screen I1 for each completerevolution of antenna I6.. The angular portion of the discontinuousportion thereof is determined byV the angular position of stationarycontact 63. Annular memberA 64 is provided with an annular gear 65, .onthe Vouter periphery thereof, which cooperates with pinion 66 wherebythe annular position of 'stationarycontact 63 is varied upon manual'rotation of pinionES through control dialV BT tavary the angularYpo'sitionfoil the discontinuous por-tion ofthe circular mark.

As' mentioned heretofore, -since the rangeilof remote objects-isdetermined by theradi'al dise tance-'of indications bfrom fthe centerof thescreen l1, andk since the direction of such objectsv is determinedVfrom the angular'position of the indications, the novel arrangementdisclosed herein provides means for determining the? range anddirectioniof remote objects from such indications with ahigh degree ofaccuracy. Capacitance 38, Vaswell as the circuit. constantsassociatedtherewith; are selectedV sothatjthe rate of exponential chargeonv the capacitance corresponds to the linearly increasing portion ofthe saw-toothwave forms appliedA to deiiection coils. It, and istherefore, at all times, equal to thev rate of radial propagation of theelectron beam of the' oscilloscope. The pulses produced at the output oftube 4l', and consequently the discontinuous circular mark produced onscreen i1, is therefore synchronously calibrated in range with Vtheremote object indications In'. Since the time-of generation or the pulseoutput of tube 41, following initiation of the radialscanning of the`electron beam, is varied upon operation ofY potentiometer 42, throughldial 43, dial 43 is calibrated-in range so that the radial positions ofthe positive pulse, with respect to the radial scanning time of theelectron beam,.is determined as aiunction of range from dial 43.Moreover, since member 60 rotates in synchronism with rotation ofantenna le, dial 51is1cali-- brated in degrees so that various angularpositions of the discontinuous portion of thegcir'- cular mark on screenl'l are accuratelyrdetermined therefrom.

When utilizing` a device havingv the foregoing characteristics foraccurately determining range and direction of a remote object from anindication b onscreen Il, dial. i3 is operated to vary the radiusof thediscontinuous concentric calibration mark in order to coincide with theradial distance. of the` indication, whiley dial'Sl is rotatedtobangularl'y vary the position of .the discontinuous portion until theremote object indication b isv symmetrically .located within''suchportion, as shown in Fig. 2V of the drawing.. The range anddirection ofthe remote object corresponding to'such indication is then directly readfrom dials 43 andA 6'! with a high degree of accuracy. .Variations inrange` and direction of the remote object is readilyobtained by properoperation of dials t3 and 6l to maintain a remote object indication .bsymmetrically within the discontinuous portion of the'circular mark.

There is thus provided by the present invention novel meansfoi-.facilitating the interpretation of. indications. produced by radioecho. ran-ging devices or similar apparatuses ofV the type. disclosedherein. Means Yare provided vby the present invention for producingdirectV indications of range and direction of a remote object from theindication thereof produced on the indicator of the apparatus. .Suchmeans is capable of producing continuous indications of range anddirection of a pre-selected remote object,v with a high degree ofaccuracy, when such object variesin range and direction to any positionyabout the apparatus.

Although'one embodiment of the present in-V vention Vhas been disclosedand describedherein,

Without'Y departing from the spirit ofthe inven-I tionasvvell understoodby those skilled inthe art. Reference therefore will be had to the ap.-pended claims for 'a definition of the limits of the invention.

This application isa continuation of application Serial Number 441,732;filed May 4, `1942,A

tinually rotating said antenna for continuallyv scanning an area aboutsaid apparatus with said directive energy, means receiving energyreflections Whenever said directive energy impinges upon and reiiectsfrom remote objects included within said scanned area, an indicatorincluding means generating an electron beam, means continually delectingthe said electron beam wherebyY said beam continually radially scans theviewing screen of said indicator in synchronism with the rate ofpropagation of said directive energy emission in a directioncorresponding to the direction of said directive-energy emission, meansmodulating the intensity of said electron beam in accordance with thereception ofsaid energy reflections for producing visual indications onsaid screen of remote ob-v jects included within said area, with theindications having certain radial distances at certain angular positionswith respect to the center of said screen in accordance respectivelywith the range and direction of remote objects With respect to saidantenna, means generating an impulse in synchronism with each radialpropagation of said directive energy emission, means varying thegenerating time of said impulse with respect to time of radialpropagation 0f said' electron beam, means applying said impulse to saidindicator for modulating the intensity of said electron beam, meanspreventing application'of said impulse to said indicator for a certaininterval during each complete revolution of said antenna whereby adiscontinuous 'circular mark is produced on said screen, means vvaryingthe angular position of the discontinuous portion of said mark, andmeans respectively -indicating the radial position of said marksl andthe angular position of said discontinuous portionA as functions ofrange and direction.

2. An apparatus for indicating positions of remote objects in spacecomprising a directional -beam antenna, means applying a sourceA ofenergy to said antenna for producing a highly directive energy emissiontherefrom, means continually rotating said antenna for continuallyscanning an area about said apparatus with said directive energy, meansreceiving energy reiiections lwhenever said directive energy impingesyupon and reiiects from remote objects included Within said `scannedarea, an indicator including means generating an electron beam, rmeanscontinually delecting the said electron beam whereby said beamvcontinually radially scans the' viewing screen of said indicator insynchronism with the rate Vof propagationof said directive energyemission in a direction corre- T9 y vspending toV the direction of saiddirective energy emission, means modulating the` intensity of said`electron beam in accordance with the receptionof said. energyreiiections for producing visual: indications ron saidscreen of remoteobtain interval during each complete revolution of said radiallypropagating beam whereby a discontinuous circular Vmark is produced onsaid screen for each complete revolution of said radially propagatingbeam, means varying the generating time of said impulses as a functionof range with respect to the time of radial propavgation of said beam,and means varying the angular position of the discontinuousportionofsaid mark as a function of direction.

3. An apparatus for indicating positions of remote objects in spacecomprising a directional beam antenna, means applying a source of energyto said antenna for producing a highly directive energy emissiontherefrom, means continually rotating said antenna for continuallyscanning an area about said apparatus with said directive energy, meansreceiving energy reflections whenever said directive energy impingesupon and reflects from remote objects included Within said scanned area,an indicator including means generating lan electron beam, meanscontinually deflecting the said electron beam whereby said beamcontinually radially scans the viewing screen 'of said indicator insynchronism with the rate of propagation of said directive energyemission in a direction corresponding to the direction of said directiveenergy emission, means modulating the intensity of said electron beam inaccordance with the reception of said energy reflections for producingvisual indications on said screen of remote objects included Within saidarea, with the indications having certain radial distances at certainangular positions with respect to the center of said screen inaccordance respectively with the range and direction of remote objectswith respect to said antenna, means generating an impulse in synchronismwith said energy emission, means applying said impulses to saidindicator for modulating the intensity of said beam at a certaininstance during each Vradial propagation thereof, means lpreventingapplication of said impulses to said indicator for a certain intervalduring each complete revolution of said radially propagating beamwhereby a discontinuous circular mark is produced on said screen foreach'complete revolution of said radially propagating beam, means.varying the generating time of said impulse with respect to the timevofradial propagation of said beam for lvarying theradius of said mark,means varying the angular position of the discontinuous portion of saidmark, means indicating the radius of said mark as a function of range,and means indicatingl the angular position of said discontinuous`portion as aifunction of direction.

4. An apparatus for indicating positions of remote objects in spacecomprising a directional beam antenna, means applying a source of energyto said antenna for producing a highly directive energy emissiontherefrom, means continually rotating said antenna for continuallyscanning an area about said apparatus with said directive energy, meansreceiving energy reections whenever said directive energy impinges uponand re,- iiects from remote objects included within said scanned area,an indicator including means gen;- erating an electron beam, meanscontinually deflecting the said electron beam wherebysaid beamcontinually radially scans the viewing screen of said indicator insynchronism with the rate of propagation of said directive energyemission in va direction corresponding to the direction of saiddirective energy emission, means modulating the intensity of saidelectron beam in accordance with the reception of said energyreflections for producing visual indications on said screen of remoteobjects includedrwithin said area, with the indications having certainradial distances at certain angular positions with respect to the centerof said-screen in accordance respectively with the range and directionof remote objects with respect to said antenna, means generating animpulse in synchronism with each radial propagation vof said directiveenergy emission, means varying the generating time of said impulse withrespect to'time of radial propagation of said electronfbeam, meansapplying said impulse to said indicator for lmodulating the intensity ofsaid electron beam, means preventing application of said impulse to saidindicator for a certain interval dur'- ing each complete revolution ofsaid antenna whereby a discontinuous circular mark is produced on saidscreen, means varying the radius of said mark to'coincide with theradius of a remote object indication, means varying the angular positionof said mark to coincide the dis',- continuous portion thereof with saidindication, and means indicating the radial position ofsaid mark and theangular position of said discontinuous portion respectively as functionsof range and direction of a remote object represented by said remoteobject indication.

5. An apparatus for indicating positions of re' mote objects in spacecomprising a directional beam antenna, means applying a source of energyto said antenna for producing a highly directive energy' emissiontherefrom, means continually rotating said antenna for continuallyscanning an area about said apparatus with'said directive energy, meansreceiving energy reflections Whenever said Adirective energy impingesupon andreiiects from' remote objects included within said scanned area,an indicator including means gen'- erating an electron beam, meanscontinually de'- flecting the said electron beam whereby said beamcontinually radially scans the viewing screen vof said indicator insynchronism with the rate of propagation of said directive energyemission in a direction corresponding to the direction of said directiveenergy emission, means modulating the center ofi` said screen'inaccordance respectively with the range and direction of .remote objectswith respect to said antenna, means generatingan impulse in synchronismwith each radial prepay `valy during eachV 'complete revolution of saidantenna whereby-a discontinuous circular mark is"produce d Von saidscreen, means varying the radiusandthe 'angular fposition of said mark1whereby said `mark is--movable Vso that -the -discontinuous portionthereofy `coincides with the remote objects indication, the lastnamedmeans 'includingmeans varyingthe lradius of said 'mark a function 'of`range, and means 4varying `the ngularposition of-said discontinuousportion as a function'o'f direction.

16.- rsnapparatusforindicating positions `of remote nbjeots'in spacecomprising a directional beam antenna, -means applying Va source ofenergy; to said antenna for -producing* a vhighly directive energyemission ltherefrom, Vmeansfcon- LtinuallyV `rotating =said Vantenna,for continually 'scanningf'an area about said apparatus with Vsaiddirective energy, means receiving energy reflections Whenever saidydirective #energy impinges upon land' Yreflects from -remote objectsincluded Within said-scanned area, van `indicator including m'eansgenerating van electron beam, means Ycontinually deflecting the saidelectron beam Whereby-said'beam continually radially scans'theviewscreen of said indicatoriin synchronism with 'therate -ofpropagation of-said directive energy memission/in avdirectioncorresponding to Athe vdi rection iof `'saicl' directiveenergy emission, means modulating the intensity of said electronabeaml:inaccordance 'with v--the :reception of lsaid lener-gy reiiections'ff'or producingv visual indications 4on saidscreenfo'f `remote objects'includedvvithinsaid area, with *the indications having certainJradial fdistances'la't `certain angular positions `with respect'ito thecenter-of said- -screen `in accordance :respectively With-fthe lrangeand direction of .reino't'eob'jeots4 with'A respect to -said antenna,means -generating'an impulse in synchronism with-each radiali'propagation` of lsaid' directive energy emission, Imeansvarying thegenerating time of said aimpulsewitli respect '.to time of .radialpropagaftionfof said .electron beam, means applying Vsaid impulse tosaid indicator ifior modulating `thein- `ltensity of said electron beam,.means preventing :application of :said .impuls-e to said ,indicator forascertain interval during each icomplete :revolution `of :said antennawhereby Aa Vdiscontinuous circulan mark 'is produced on said screen,means `varying:atheradius and-the angular position'of to. said 'antennafor producing a vdirectional radio pdlseemission means rotating saidantenna for scanningian area Aextending 360 about said an- Y Y 1'2'tenna Withsaidfdirectional radio pulse emission, -a cathode -rayindicator, means producing -a radial sweep onithescreen of saidindicator synchronizedwith said radio pulse emission, ,means rotatingsaid sweep in synchronism :with :rotation of `said Vdirectional radiopulse emissiom-a radio .pulse receiverfor .receiving echo pulsesWhenever said radio pulses impinge uponand reect from 1remote objectsincluded within said scanned area, means applying said echo pulses tosaid rindicator 'foriproducing remote objectindications on said screen:at different radial distances-and angular positions withrespectitothecenter ofrsaid:screenvcorresponding to range and direction Yof remoteobjects with respect Ato .said antenna, means producing .a discontinuouscircular mark on said screen, means varying the radius of-fsa'id mark tocoincide with the'radius of a remote object indication, means'varyingtheangular position of said mark to coincide the dis.- continuous portionthereof with said indication, and. means respectivelyindicating theradial position -of said mark and the angular position fofsaiddiscontinuous portionas functions of-range and direction of theremote object'represented by saidvremote object indication.

8. In combination, V'a ydirectional echo .ranging system `including Vatransmitter and a receiver voperative yto determine range and directionof 'remoteobjecta a two coordinate'cathode ray type Aobject range anddirection indicator, cathode ray -intensity control means Vfor -saidindicator, :pc-

'tential generating' means for Agenerating a -po- `tentialprogressivelyincreasing with time, means REFERENCES CITED The followinglreferences are of recordin the iilc of this patent:

UNITED STATES PATENTS Number Name Date 1,930,945 Sjostrand Oct. 17,19332,189,549 'Hershberger Feb. 6, 1940 '2,202,634 Mack May 28, 19402,235,177 Stark Mar. 18, 1941 2,264,279 Dearing Dec. Y2, 1941 2,267,715Bowen Dec. 30, 1941 2,300,189 Woli Oct. 27, 1942 '2,307,029 Elm Jan. 5,1943 2,405,238 Seeley Aug. 6, 1946 '2,423,104 Labin July 1,19472,432,196 HershbergerA Dec. 9, 1947 v2,445,213 vEvans July 13, 1948'2,455,673 Hansell Dec. 7, 1948 2,468,032 Busignies Apr. 26, 1.949'2,471,516 ,'Bryant May 3l, 1949 FOREIGN PATENTS 'Number Country Date108,556 Australia .Sept. 14, 1939

